Darryl Frink knows a thing or two about Lycoming IO-540s. As the director of maintenance for Central Air Southwest, he has overhauled nearly 1,000 engines in his 40 years at the company.
Central Air Southwest owns 30 Twin Commander 500Bs, about 25 of which are currently operational. Because each airframe flies about 30 hours a month, they are authorized to perform overhauls at 1,800 hours. According to Frink, about 80 percent of their engines make it to TBO. “At that point the main bearings are telling us it’s ready,” he said.
Rarely does the company have to perform top overhauls or other mid-cycle major maintenance. Occasionally they’ll have one break a crankshaft, but often a faulty part from the manufacturer or a gear-up landing will result in a premature trip to the overhaul shop. Other than that, they change the oil at the 100-hour inspection, use oil screens, and replace the magnetos at 900 hours. Frink said the magnetos will go 1,000 hours, but the mid-point time on the engine makes more sense.
Because of the volume of work, the company field overhauls all their engines. Crankcases, crankshafts, rods, and some other parts are sent out for reconditioning or replacement, and a local contractor assembles the engine. Frink and his team pull the engine, manage the process, and remount and test the finished product. The entire process takes about eight weeks, and he aims for six engines in rotation at any one time. That has him putting one on and testing it every two weeks.
Over many years of trial and error the maintenance team has honed the process to reduce failures, reduce downtime, and save the company money. About 20 years ago they had terrible problems with rods being thrown. It turns out Lycoming had changed the part number and came out with a better design, which Central Air Southwest quickly adopted. Currently CAS is working on a modification to include an oil filter on the guidance of the tech who works on their crankcases. “It’s like when you walk down the stairs and hit the coffee table at the same spot every day,” he said. “You learn pretty soon to take a different route.”
It’s no secret that regularly exercising a piston engine is the best thing you can do to keep it running smoothly. Flying 30 hours a month certainly qualifies, and no doubt has a major impact on the reliability of Central Air Southwest’s engines. Frink has four pieces of advice for owners who want to help extend the life of their engines, based on the company’s standard operating procedures.
- If it’s 20 degrees Fahrenheit or less, preheat the engine or put it in a hangar. Lycoming’s guidance says to preheat starting at 10 degrees, so Frink takes a slightly more conservative approach.
- Don’t go over 1,000 rpm until the cylinder heat temperatures and oil temperature are in the green.
- Don’t let the engine drop more than 100 rpm on a feather check. The manual calls for a drop from 1,500 to 1,000 rpm, but Frink doesn’t think that’s necessary.
- Make slow and steady throttle changes.
You most likely don’t fly your Commander 30 hours a month. Doing a few little things to help baby your engines will help ensure they stay happy and healthy.
